7. Income taxes

The Company accounts for income taxes in accordance with ASC 740—Income Taxes. Under ASC 740, income taxes are recognized for the amount of taxes payable or refundable for the current period and deferred tax liabilities and assets are recognized for the future tax consequences of transactions that have been recognized in the Company’s financial statements or tax returns. A valuation allowance is provided when it is more likely than not that some portion, or all, of the deferred tax asset will not be realized.

The Company accounts for uncertainties in income tax in accordance with ASC 740-10—Accounting for Uncertainty in Income Taxes. ASC 740-10 prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. This accounting standard also provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosure and transition.

The Company recognizes interest and penalties on taxes, if any, within its income tax provision. No significant interest or penalties were recognized during the periods presented.

The Company operates in multiple states. The statute of limitations has expired for all tax years prior to 2012 for federal and 2011 to 2012 for various state tax purposes. However, the net operating loss generated on the Company’s federal and state tax returns in prior years may be subject to adjustments by the federal and state tax authorities.

Income tax expense was $1,994 and $982, an effective tax rate 36.6% and 26.7%, for the three months ended September 30, 2016 and September 30, 2015, respectively. Income tax expense was $5,929 and $3,683, an effective tax rate 35.1% and 32.3%, for the nine months ended September 30, 2016 and September 30, 2015, respectively. The increase in the effective tax rate was primarily due to the tax benefit adjustments that occurred in the third quarter of 2015 partially offset by research and development credits allowed in the third quarter of 2016, but not in the comparative period in 2015.